Vokera Boiler Fault Problems And Cures

The Vokera boiler fault problems and cures Q & A or require an engineer for an emergency boiler repair.

The Vokera Boiler Fault Problems And Cures Common Q & A

Below we’ve created a detailed guide to the most common problems with Vokera boilers, and the potential cures.

Vokera Boiler Fault Problem And Cures

When a problem occurs with your Vokera boiler, it will display a fault code on the display panel. These fault codes help a boiler engineer narrow down the problem to a few potential causes.

Some fault codes are highly specific (for instance, the fan is running to fast), where as others are slightly more generic (for instance, the boiler is losing pressure).

When a fault code is displayed on your Vokera boiler, you shouldn’t reset the appliance to try and clear the code. Although the reset might temporarily trick the boiler into thinking that the problem is fixed, there are two main reasons why you shouldn’t do this:

  • 1. The boiler has locked out to prevent it operating, as continued operation would be dangerous (i.e. a gas valve that is letting-by/leaking)
  • 2. The boiler has locked out to prevent internal components getting damaged (i.e. boiler overheat detected via the NTC flow thermistor, which could lead to parts such as the heat exchanger cracking)

So, the idea of a boiler lock out is to protect you, your family, and your boiler.

If a fault code is displayed on your boiler, you need to call an emergency boiler repair engineer to find the fault and fix the problem. Once they’ve fixed the problem they will reset your boiler on your behalf, which will clear the fault code.

The most common problems on Vokera boilers are listed below, including:

What does the _CL fault code mean on Vokera boilers?

If your Vokera boiler is showing the _CL fault code on the display panel, it means that it needs a service.

Boilers should be serviced on an annual basis by a qualified engineer. There are 24-hour boiler engineers that will be able to be able to complete this service.

They don’t necessarily have to be from the Vokera service team, but they do need to be Gas Safe registered. It’s only Gas Safe registered heating engineers that are legally allowed to repair, maintain and service boilers.

You should expect an annual service to cost in the region of £70-100. This is a rough estimate from independently owned companies, rather than large national boiler companies. Many of the larger companies charge upwards of £110 for their boiler services.

When a boiler engineer services a boiler, they will inspect your boiler for any obvious signs of wear. Essentially, they’ll be able to determine which parts of going to break, before the breakage happens.

Alongside this, they’ll run a series of tests to ensure that your boiler is working efficiently and safely. This includes testing things such as flue gases, using a flue gas analyser.

If you have a scale reducer (which catches limescale) and a magnetic system filter (which catches central heating sludge), your boiler service engineer will be able to clean them out during the service. These filters help to catch debris which would otherwise block up expensive parts such as the pump, heat exchanger and even radiators.

For that reason, if you don’t have a system filter or scale reducer fitted, it’s worth speaking to your service engineer and getting a quote to have one of each fitted. Both filters will help keep your boiler running smoothly and prolong its life.

A boiler service should only take a couple of hours, although this may take a little longer if you require filters cleaning.

And it’s worth noting, if any issues are found with your boiler, the repair will be at an additional cost.

My boiler is displaying the A01 fault code, what does this mean on Vokera boilers?

The A01 fault code on Vokera boilers relates to an ignition fault. That limits your emergency boiler engineer’s fault-finding mission to either ignition, or ignition sensing faults.

The first thing your boiler engineer will want to check is that the flame sensor is operating correctly. The A01 fault code suggests it’s a flame/ignition failure, but this could just as easily be a flame sensor fault. The flame sensor could be telling the printed circuit board (PCB) that a flame is present, even when it’s not (and, vice-versa).

If the flame sensor has been ruled out as the issue, they’ll need to check the ignition lead and probe. If these are old and worn, it could be these components causing the ignition failure, and they can be tested for power using a multi-meter.

But, before a replacement is called for, the emergency heating engineer needs to check that it’s not moisture causing these items to fail. If it is, they’ll need to remove the moisture from the components, but also find the source of that moisture.

It’s most likely a leak that’s led to moisture build-up, and this needs to be fixed before it causes problems to other expensive boiler parts.

If all the above issues have been ruled out, it’s likely the A01 fault code relates to a problem with the gas valve.

It’s the gas valve that moderates the flow of gas to your boiler. Over time, gas valves are prone to getting stuck. When they do, they won’t be providing the boiler’s burner with a sufficient amount of gas (assuming, it’s stuck closed).

Sometimes, a gas valve can be freed. If the boiler engineer manages to free the valve, it can be refitted. However, if it’s still showing signs of sticking, it makes much more sense to replace the gas valve (approximate cost of £300), rather than having to call an engineer out to fix the same problem in the future.

If all the above seems in order, the issue could relate to the printed circuit board, as this is what controls the gas valve. Your emergency boiler repair engineer will be able to test this using a multi-meter to check this is the problem.

If my Vokera boiler is showing the A03 fault code, what does this mean?

The A03 fault code on Vokera boilers relates to a fan fault. Specifically, it relates to a tacho signal issue.

When the A03 fault code develops on a Vokera boiler, it’s likely to start working intermittently. Usually, the cause is down to old age, or due to an internal boiler leak that’s caused issues with wiring and connections.

If the A03 fan fault occurs, alongside intermittency, the boiler’s fan might suddenly be running at a speed that’s too low. This is dangerous and is going to cause the boiler to lock out.

Your boiler’s fan helps to create a draught. This in turn, helps to push harmful gases up and out of the flue. So, if the fan isn’t running at the correct speed (or its operation is intermittent), the boiler is going to be dangerous.

An emergency boiler repair is likely to start by checking the connections and wiring to the fan. If there are signs of obvious loose connections or damaged wiring, that’s going to be the cause of the A03 fault code.

However, it’s more likely that there’s an internal boiler leak, causing moisture to settle on the fan. Some older boilers don’t have electrical units (including the fan) that are sealed well. That means that when there’s a boiler leak, this moisture can get into all electrical components and cause expensive damage.

A worst-case scenario is going to be that your boiler needs a new fan. When this is the case, you should expect to pay upwards of £250.

However, it’s incredibly important to ensure that the boiler engineer fixes the problem that caused the issue in the first place (the leak), otherwise this isn’t just going to ruin the fan, it will ruin other boiler parts as well.

My boiler is showing the A04 fault code, what is the problem and the fix?

The A04 fault code is one of the most common problems with Vokera boilers; it relates to low boiler pressure.

The pressure in your boiler is displayed on a pressure gauge, this is usually located on the display panel, or beneath the boiler’s casing. The pressure being shown should be around 1.3 bar, although this will increase slightly as the boiler heats up (dropping again, as the boiler cools down).

Boiler pressure is directly related to water in the system. And, this water can be topped up using the external filling loop that is below your boiler; it’s a small braided hose with valves on it. To top up your boiler pressure, you’ll need to open the valve on the filling loop.

But, you shouldn’t do this if you’ve noticed your boiler pressure dropping. A reduction in boiler pressure means that there’s a leak in the heating system. This loss of pressure obviously means a loss of water too.

The question is, where is that water going? We’ve seen instances of people topping up their boiler every time pressure drops, for months. Then months later when the leak is found, it’s either leaked on plaster and floorboards (rotting them completely), or even worse, has leaked on expensive boiler parts such as the PCB. And, parts like this can cost over £500 to replace.

So, whilst topping up your boiler pressure is an easy task, you need to think about what is causing the pressure loss. An emergency boiler repair engineer will be able to fault find your heating system to figure out where the leak is coming from and fix it.

This leak could be anything from a soldered copper pipe joint that has broken free, a cracked heat exchanger or even a pin hole in a radiator.

My Vokera boiler is showing the A06 fault code, what does this mean?

If your Vokera boiler is showing the A06 fault code, it means there is a problem with the domestic hot water (DHW) sensor.

Boilers have a range of thermistors. These measure resistance (in ohms). These resistance readings are constantly fed back to the printed circuit board. Essentially, they keep the PCB informed of water and heating temperatures.

When water gets to the desired temperature, the PCB knows thanks to these thermistors, and it can cut off the supply of gas to the burner. Similarly, if the water isn’t up to temperature based on these readings, it knows that the burner needs to continue to operate.

In the case of the A06 fault code, the PCB has recognised a fault with the DHW thermistor. It’s likely that the DHW sensor is simply faulty and needs replacing. And, in terms of emergency boiler repairs, this is usually a cheap one, costing less than £100.

In some cases, it could be the wiring and connections that are causing the fault. If these are loose or damaged, it’s likely a small repair can be made to fix the AO6 fault code, rather than spending time and money replacing the sensor.

However, before replacing anything, your heating engineer needs to check that it’s not a fault with the PCB that’s causing the problem. The PCB controls every electronic component in your boiler. So, if the PCB malfunctions, almost everything in the boiler will too. And, this could mean that the fault code being displayed is incorrect.

Your emergency boiler engineer can test the PCB using a multi-meter. Unfortunately, PCBs are expensive parts to replace. If you need a replacement PCB, you should expect to pay somewhere in the region of £450-550, depending on the exact model of boiler that you have.

My Vokera boiler is showing the A07 fault code, what does this mean, and can it be fixed?

When Vokera boilers show the A07 fault code on the display panel, it means there is a problem with the NTC thermistor on the flow side of the boiler.

The NTC thermistors on your boiler monitor the flow (hot water leaving the boiler) and the return (water that’s travelled around the heating system and is returning to the boiler to be reheated). There is a maximum temperature differential between these two NTC thermistor readings. Once this differential has been exceeded, the boiler will lock out and show the A07 fault code.

There are a few things that cause the maximum temperature differential to be reached, but one is a circulation fault.

Typically, your emergency boiler engineer is going to want to check the operation of the pump. If the pump is working, but has restricted flow, it will circulate water through the flow thermistor (at the desired temperature). But, because of the slow water flow, by the time water reaches the return thermistor, it’s temperature has dropped considerably, causing the reading to exceed the maximum differential.

Causes of a circulation faults with the pump include heating sludge, air locks and even incorrect installation. Your 24-hour boiler technician will be able to check for sludge (cleaning if necessary), remove air locks and ensure that the pump has been installed with the pump’s shaft horizontal.

To ensure it’s not the pump causing the issue, they’ll also need to check the pump’s bearings aren’t fully or partially seized, as this would restrict the pump’s ability to circulate water.

Next, they’ll want to know if your system has anything to combat limescale, such as limescale inhibitor or a scale reducer. Where limescale forms (and, it can form near the NTC thermistor on the flow), the water will burn hotter, producing a temperature reading that is inconsistent with the rest of the water in the system.

The same can happen on the heat exchanger, causing it to overheat and eventually lead to the component cracking. If this is the case, it’s likely you’ll have noticed a whistling noise recently.

With all those issues checked out, the conclusion is likely that it’s the NTC thermistor that is faulty. A simple replacement will fix the problem and clear the A07 fault code.

If the A08 fault code is being displayed on my Vokera boiler, what does it mean?

The Vokera A08 fault code is similar in a way to the A07 fault code, as it relates to a temperature differential issue. The difference here, is that the common cause is that the temperature differential is the wrong way around; the flow pipe is colder than the return pipe.

The flow on the boiler should always be hotter than the return. This is simply because water leaves the heat exchanger with help from the pump via the flow, after it’s been heated. It then travels around pipework, radiators and towel rails. These heat your house by absorbing the heat from this water, meaning that when the water eventually arrives at the return pipe (ready to be reheated by the boiler), it’s lost a considerable amount of temperature.

An uncommon fault, is that the NTC thermistors have been fitted on the wrong pipes. This is only likely the case if the boiler is brand new (manufacturer installation fault) or the NTC thermistors have been replaced (boiler engineer installation fault).

A more common cause is that the return thermistor is faulty. Luckily, thermistors on boilers are cheap. Parts can be purchased for £20-30, with the installation of a new thermistor (including parts) being less than £100.

Your boiler engineer will be able to check that this is the case, by testing the NTC thermistor. They’ll check the thermistor is providing the correct readings. If it is, then it’s likely the PCB that’s at fault rather than the thermistor.

The PCB monitors the readings given by the thermistors, so it knows what to do next (tell the burner to turn off/turn on, tell the gas valve to open etc). If the

For more PCB is malfunctioning, the readings (and the actions it takes based on these readings) are going to be incorrect.

But, the fault could just as well be the same as the A07 fault code, but incorrectly diagnosed by the PCB. That means the fault is much more likely to relate to a circulation issue, which can be fixed by diagnosing and repairing the central heating pump on your Vokera boiler.

My boiler keeps displaying the A11 fault code, what is the probable cause of the problem, and how can I fix it?

The A11 fault code on Vokera boilers relates to a false flame.

Firstly, there is a good chance that this is a gas related fault. More than ever, it’s important that you don’t reset your boiler to get it working again. Whilst the reset might allow the boiler to operate for a few minutes, it won’t fix the problem. And, that means you might have a boiler operating that could be dangerous.

Typically, a false flame fault is a boiler that still senses a flame, even though there’s no demand for the burner to be operating. The most common cause of the fault is a gas valve that is sticking.

The gas valve is operated by the printed circuit board (PCB). When you turn on taps or your heating thermostat, the PCB tells the gas valve to open, allowing gas into the burner.

In this case, gas could be still letting-by, allowing gas into the burner even when it shouldn’t, causing a flame to occur when it shouldn’t.

Your gas engineer will be able to check that the valve isn’t getting stuck. It’s a frequent problem with old gas valves that they get stuck partially closed. And, that’s going to let-by gas.

In some cases, the valve can be freed and refitted. However, it’s more likely that your emergency boiler repair engineer is going to suggest a replacement. And typically, we’d expect that to cost in the region of £250-300.

If the gas valve isn’t letting-by, the problem here is a sensing issue. The most probable cause of this sensing fault is going to be the flame sensor. These are easy to test and cheap to replace.

But, if the gas valve isn’t sticking and the flame sensor isn’t faulty, it could be a malfunctioning PCB. When a PCB malfunctions, it’s not going to give or receive the correct signals to other boiler parts. And, as it’s the PCB that controls all important electronic components, the boiler is going to work intermittently.

Unfortunately, these are not cheap to replace. A typical PCB replacement could cost £450-550 and take around 1 day to install.

Other boiler issues relating to other manufactures

For more boiler issues then please visit the Boiler Problems And Cures page.